Re: X82-37R: Waterfallter Return
You proceed down the circular metal tunnel, though the floor has a span across the width that makes it a flat surface. No doubt the utilities, whatever they might be, are running under the floor.
A tap on the wall indicates that the metal of the wall is pretty thick, and that there is probably concrete or something similar surrounding it. It's even possible that the tunnel was bored through the bedrock.
About every 60 feet, you come to a reinforced airlock. There are manual levers on the external side of the airlock that push large bars into slots in the wall. The idea seems to be that as you fled, you could secure each hatch behind you to prevent pursuit. These hatches are all closed, but none of them are locked, so they are easy to open.
After passing through 10 of these hatches, the tunnel continues but there are two side tunnels that head off at angles to either side. You see yet another hatch down each tunnel. Since none of the tunnels slant up or down, it's a reasonable guess that the facility wasn't stacked but sprawled out.
Heading straight, you go through the next hatch and you are in the main complex.
The tunnel gives way to a regular hallway that runs about 70 feet. It's intersected at the middle be a cross-hallway. Along both sides are glass walls that show offices behind them.